Switch and signal control system for railroads



July 28, 1942. s N, w|GHr 2,291,425

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Patented July 28, 1942 SWITCH AND SIGNAL CONTROL SYSTEM FOR. RAILROADS Sedgwick N. Wight, Rochester, N. Y., assigner to General Railway Signal Company, Rochester, N. Y.

Application April 10, 1940, Serial No. 328,907

7 Claims. (Cl. 246-134) This invention relates to switch and signal control systems for railroads, and it more particularly pertains to such systems of the entrance-exit type.

In arl entrance-exit system, a control machine is located at a control oilice for governing the power operation of track switches and the clearing of signals in setting up the various routes extending through a track layout. The principal part of the control machine is a control panel upon which is a miniature track diagram corresponding to the track layout in the eld for which the system is provided. Disposed at points corresponding to signal locations on the miniature track diagram are control buttons for designating, when actuated by an operator, the respective entrance and exit ends of each route to be established. Thus, in a system of the entrance-exit type, each route is set up in accordance with the designation of the entrance and exit ends of such route by an operator. In order to determine the direction for which a signal shall be cleared for each route set up, separate entrance and exit buttons can be provided for each signal, thus requiring that an operator designate the direction by selecting which button he shall actuate for each route end. Another means for deiining the direction for which a signal shall be cleared for each route set up is to provide a single push button for each route end,

and depend upon the sequence in which an operator actuates the buttons for the respective entrance and exit ends of each route to define the direction. It is to this means that the present invention more particularly pertains, although, certain of the novel features provided by the present invention are applicable to entranceexit systems having separate buttons for entrance and exit designation for each route end.

An object of the present invention is to provide an improved circuit means for determining the direction for which a signal is to be cleared in accordance with the sequence of operation of single buttons for the opposite ends of each route in an entrance-exit system. Such circuit means as provided by the present invention is adaptable for use in any entrance-exit system of the general type shown, for example, in the patent to A. Langdon, Patent No. 2,148,865, dated February 28, 1939, and in my prior application, f

Ser. No, 275,923, filed May 26, 1939, now U. S. Patent No. 2,265,258, granted December 9, 1941.

In accordance with my above mentioned prior application, the designation of an entrance point in setting up a route causes energy to feed through branches of a circuit network arranged in conformity to available routes emanating from the entrance point designated. Such circuit network is conveniently called an "initiating network. The designation of an exit point causes a route to be completely established only if there is an entire branch of the initiating circuit network which corresponds to a route available for use extending between that exit point and an entrance point which has been designated. The establishment of each route is eiected in accordance with the energization of a circuit network known as a completion network for the selective energization of normal and reverse switch control relays.

Another object of the present invention is to cause the illumination of an indicator lamp, responsive to entrance designation, for each exit point included in a route available :for use extending from that entrance point, such indicator lamp being illuminated because of the energization of a relay for that exit point by the initiating network.

Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawings, and in part pointed out as the description of the invention progresses.

In describing the present invention in detail, reference will be made to the accompanying drawings in which corresponding parts are designated throughout the several gures by like reference characters, in which those parts having similar features and functions are designated by like letter reference characters which are generally made distinctive either by reason of preceding numerals or by preceding letter reference characters which dene the signal locations with which such parts are associated, and in which:

Figs. 1A and 1B, when placed side by side, illustrate a miniature track diagram corresponding to the track layout for which the system in this embodiment of the present invention is provided, together with route establishing means and signal clearing means effective to select each route and clear the entering signal in accordance with the actuation by an operator of entrance and exit buttons on the track diagram;

Fig. 2 illustrates the track layout for which the entrance-exit system in this embodiment of the present invention is provided, together with circuits pertaining to the operation of the track switches; and

Figs. 3A and 3B illustrate a modification of the system shown in Figs. 1A and 1B to provide indications on the track diagram by means of lines of light for illumination of the portions corresponding to routes established.

In order to simplify the description of the present invention, reference is made from time to time to functions characteristic of a particular group of devices by use of letter reference characters common to such devices without their distinctive preceding numerals or letters representative of the signal locations with which such devices are associated. It is to be understood that such reference applies in general to parts designated in the drawings by letter reference characters which are similar except for preceding numerals or preceding letters representative of signal locations.

The various devices and circuits constituting the embodiment of the present invention have been shown diagrammatically and conventional illustrations have been employed for the purpose of facilitating the disclosure of the present invention as to the mode of operation and the principles involved, rather than for the purpose of attempting to show the specific construction and arrangement of parts that would be employed in practice. Thus, symbols are employed to indicate the connections to terminals of batteries or other sources of electric current instead of showing all of the wiring connections to such sources, and relay windings and contacts are illustrated by conventional symbols, corresponding reference characters throughout the drawings being used to identify contacts provided on the same relay.

The symbols (-l) and are employed to indicate the positive and negative terminals respectively of batteries or other suitable sources of direct current, and the circuits with which those symbols are used always have current owing in the same direction. Ii alternating current is to be used in place of direct current, the particular symbols employed represent relative instantaneous polarities.

Track layout-With reference to Fig. 2, the track layout for which this embodiment of the present invention is provided consists of two parallel tracks connected together by a crossover TS having track switches TSA and TSB, track switch TSA being associated with the upper track, and track switch TSB being associated with the lower track. It is to be understood that the simple track layout used in this embodiment of the present invention is employed to simplify the description rather than to limit the application of the present invention to other track layouts, as the system can be readily expanded to satisfy the requirements for practically any complex track layout encountered in practice. That is, the circuits provided for governing train movements over the single crossover shown in Fig. 2 are typical of circuits which would be provided for additional Crossovers and for single track switches.

Trailic through the track layout is governed by signals A, B, C and D, signals A and B being provided for governing east bound traffic to the right, and signals C and D being provided for governing west bound trafc to the left. The signals illustrated are of the type having individual color lamp units, the lower lamp providing a red danger indication and the upper lamp providing a green clear indication. It is to be understood that additional indications can be provided as required in practice, and that other types of signals can as well be employed, such, for example. as search light and semaphore signals.

The switches TSA and TSB are power operated by a switch machine SM of a suitable type such as that shown, for example, in the patent to W. K. Howe, Patent No. 1,466,903, dated September 4, 1923, and the motor of the switch machine can be provided with overload protection and other features commonly employed in practice in a suitable manner such as that shown, for example. in the patent to W. H. Hoppe et al., Patent No. 1,877,876, dated September 20, 1932. For the purpose of simplifying the present disclosure only one switch machine has been shown for the power operation of the track switches TSA and TSB, but it is to be understood that a separate switch machine can be provided for the operation of each track switch in accordance with the requirements of practice.

The locked position of the track switches TSA and TSB in correspondence with the switch machine SM is repeated in the usual manner by a polar neutral switch repeater relay WP. Such relay being energized with one polarity when the switch points and the switch machine are locked in a particular position, and with the opposite polarity when the switch points and switch machine are locked in the opposite position. The relay WP is dropped away whenever either of the track switches, and/or the switch machine SM are unlocked or are out of correspondence with each other.

The track layout is divided into track sections in the usual manner, the track section 2T on the upper track providing track circuit control (not shown) for the track relay 2TH, and the track section 3T on the lower track providing track circuit control (not shown) for the track relay STR. It is to be understood that the track switches are bonded in accordance with the usual practice and that the usual type of track circuits is employed.

System devices-At the control oilice a miniature track diagram is constructed upon the control panel of the control machine as illustrated in Fig. 1A to correspond with the track layout in the eld for which the system is provided. Upon such diagram is disposed a route end control button NX for each point corresponding to each route end as defined by the location of the wayside signals at the track layout. Each of the Y buttons NX is of the self-restoring push button type having a contact closed only when the button is depressed, and having another contact closed when the button is in either its normal or depressed position, such contact being opened if the button is pulled out. It is to be understood that buttons having other distinctive operating positions than those shown and described in this disclosure could as well be used providing they fulfill the proper contact requirements. The construction of a button suitable for use in accordance with the present invention can be provided, for example, in accordance with the control button disclosed in the prior application of J. F. Merkel, Ser. No. 158,720, led August 12, 1937.

An entrance relay NR is provided for each of the entrance points in the track layout, such relay being energized responsive to the designation of an entrance point at that route end, and being maintained energized, dependent for restoration upon passage of a train past that entrance point or dependent upon the designation of such restoration by an operator upon the pulling out of the button NX for that route end.

A slow acting relay XK is provided for each exit point, and such relay is responsive to the designation of an entrance point for an available route having that point as exit, such relay remaining energized only so long as that route remains available, and only until an operator has designated that exit point by the actuation of the button NX for that point in the establishment of a route. Thus, these relays XK may be conveniently termed preliminary exit relays.

A usual exit relay XR is provided for each exit point, and such relay is energized upon depression by an operator of the button NX for that route end, only if the preliminary exit relay XK for that route end is picked up at that time. The energization of each XR relay causes a stick circuit to be established for that relay to maintain it energized, dependent for deenergization unon the dropping away of the entrance relay NR for the entrance end of the route including that point as exit. For convenience in distinguishing as a matter of terms from the preliminary exit relay XK, these usual exit relays XR may be termed ilnal exit relays.

The relays AY and BY are provided in the initiating network, relay AY being associated with track switch TSA, and relay BY being associated with track switch TSB. Each Y relay is energized responsive to the designation of an entrance point if that track switch is included in an available route emanating from such entrance point and is trailed in a normal position in such route. In other words, these relays serve to preselect the positions of the switches which bear a trailing point relation to the designated entrance point and are thus aptly termed preselecting relays.

The relays AN, BN and R are neutral switch control relays selectively energized in accordance with the energization of the exit relays XR, and in accordance with the position of the relays Y.

The relays NCR and RCR are respective normal and reverse correspondence relays energized when the track switches are in correspondence with their positions last called for by the enerl gization of a neutral switch control relay AN, BN or R.

The relay WZ (see Fig. 2) is a polar neutral relay which causes the operation of the track switches in accordance with the normal or reverse neutral switch control relay energized. The relay WZ provides features generally required in practice such as the follow-through of the track switch (once operation has been initiated), and a means for reversing the switch mai chine in mid-stroke.

The lock relays L are normally energized relays which govern the safe operation of the switch machine SM in accordance with the well known requirements of practice. That is, the relay 2L, for example, includes in its control circuit (not shown) detector, route, and approach locking, as required in practice. The lock relay 2L can be controlled, for example, in accordance with the circuits illustrated for relay 8L in my above mentioned prior application Ser. No. 275,- 923, filed May 26, 1939.

A normally energized lock relay LS is used to repeat the energized position of the lock relays 2L and 3L, and to open the control circuit for the switch machine SM after its operation has been completed prior to the clearing of a signal governing entrance to each route.

An indicator lamp XE is provided for each exit point in the track layout and is illuminated whenever the relay XK for that exit point is energized. That is, the designation of an entrance point in the establishment of a route causes the illumination of an exit indicator lamp XE for the exit point for each available route emanating from the entrance point which has been designated by an operator, so that these lamps may be termed available exit point indicators. When the route having its entrance point designated is completely selected after designation of an exit point for that route, the available exit point indicator lamps XE are all extinguished, except when the modified form of control shown in Fig. 3 is used.

An indicator lamp NE is provided for each entrance point, and such lamp is illuminated by steady energization to indicate a clear signal at that entrance point. If that entrance point has been designated but the signal has not yet been cleared, the indicator lamp NE for that route end is flashed to indicate such a condition, in accordance with frequent interruptions of the energy for that lamp by a coder CD.

With reference to Fig. 1A an indication as to the position of the track switch and/or the called for position of the track switch is provided by a magnetically operated switch point indicator ts on the control panel, such indicator being governed in accordance with the polar contacts of the switch control relay WZ. Indications as to the called for and/0r locked condition of the track switches TSA and TSB are provided by the normally dark lamps ALE and BLE respectively, each of such lamps being energized whenever its respective track switch has its position called for by the energization of a normal or a reverse switch control relay for that track switch or whenever the lock relay L for that track switch is dropped away. Track indicator lamps 2TE and 3TE are normally dark and are energized upon the occupancy by a train of their respective track sections.

With reference to Figs. 3A and 3B a modification shows indications provided by light sections 2, 3, 4, 5, (i, 1 and 3, each light section having a white and a red lamp for its illumination.

As an auxiliary means for governing the track switches TSA and TSB, an auxiliary lever SML is provided cn the control panel.

Having thus considered the apparatus provided in accordance with the present invention, the organization of such apparatus and the principles involved in its operation will hereinafter be considered with specific reference to certain typical operations.

Operation For the purpose of describing the present invention, it is assumed that the conditions of the system are normal when the track layout (see Fig. 2) is unoccupied by a train, when the indicator lamps on the control panel (see Figs. 1A and 3A) are dark, and when there are no routes established through the track layout. Thus, the relays are normally deenergized as illustrated except for the relays (see Fig. 2) 2L, 3L, LS, WP, ZTR. STR and NCR. The relays 2L and 3L are normally energized by the energization of circuits dependent upon the detector, approach and route locking provided in accordance with the requirements of practice. The relay LS is normally energized in accordance with the energized position of the relays 2L and 3L, by the energization of a circuit closed from (+)l including front contact 20 of relay 2L, front contact 2| of relay 3L,

back contact 22 of relay WZ, and winding of relay LS, to The relays 2TR, 3TR and WP are energized in accordance with the usual practice, and the relay NCR is energized to correspond with the normal position of the track switches TSA and TSB. Those track switches are assumed to be in a normal position to correspend with the last route set up, which is assumed to have been a through route on either of the two parallel tracks. Relay NCR is energized under normal conditions by a circuit closed from (-1-), including back contact 23 of relay R, Winding of relay NCR, polar contact 24 of relay WP in a right hand position, and front contact 25 of relay WP, to

Having thus considered the normal conditions as they have been assumed, consideration will now be given to the general mode of operation of the system in the establishment of a route through the track layout, and the clearing of the signal governing entrance to such route. For example, assume that an operator desires to set up a route from signal A to signal D at a time when the normal conditions of the system exist as they have been described. To initiate the establishrnent of such route the operator designates the entrance point at signal A by the depression of the button ANX, and, responsive to the depression of that button, relay ANR is picked up for that entrance point and is maintained energized by a stick circuit. When relay ANR is picked up an indicator lamp contained in the button ANX starts to flash, thus indicating that initiation has been effected for that entrance point.

Upon the picking up of relay ANR, energy feeds through the initiating network over each branch of the network corresponding to each available route emanating from that entrance point, and causes the energization of a preliminary exit relay XK for each of the exit points which can be included in an ava'lable route extending from the entrance point which has been designated. Thus, relays CXK and DXK are energized in accordance with the picking up of the relay ANR for the entrance point at signal A. Upon the picking up of these XK relays, the indicator lamps CXE and DXE are illuminated for those respective exit points, thus indicating to an operator that either of those points can be included in an available route emanating from the entrance point which has been designated. Therefore, the illumination of the lamp DXE. informs an operator that a route is available extending from signal A to signal D, and that such route will be established upon designation of an exit point at signal D by the depression of button DNX. After an operator has depressed the button DNX, the nal exit relay DXR responds, and a stick circuit is closed for that relay to maintain it energized, dependent upon the picked up position of the entrance relay ANR for the entrance end of that route. The picking up of relay DXR causes the relay DXK to be dropped away and the indicator lamp DXE to be extinguished.

The picking up of relay DXR causes the energization of relay R for selecting the reverse position for the track switches of the crossover TS, and the relay R, in picking up (see Fig. 2), causes the relay WZ to be energized with the proper polarity to cause the operation of the switch machine SM to a reverse locked position. The picking up of relay R causes the correspondence relay NCR to be dropped away, and, after the track switches of the crossover TS have been properly positioned, the correspondence relay RCR is picked up. The relay LS is then dropped away to open the control circuit extending to the switch machine SM, and to close a circuit for the energization of the signal control relay AG (see Fig. 1A). The picking up of relay AG causes the red lamp in signal A to be extinguished and the green lamp to be illuminated. The picking up of relay AG also causes the lamp ANE to become steadily energized to indicate to the operator that the signal governing entrance to the route from signal A to signal D has been cleared.

To consider specifically the circuits which provide the above described general mode of operation, assume that an operator initiates the designation of a route from signal A to signal D, when the normal conditions of the system exist, by the depression of the button ANX. Under such conditions, the relay ANR is picked up by the energization of a circuit closed from including front contact 26 of relay ZTR (see Fig. lA), winding of relay ANR, back contact 21 of relay AXR, back contact 28 of relay AXK, and contact 29 of button ANX closed in a depressed position, to The picking up of relay ANR causes a stick circuit to be established for that relay closed from including front contact 26 of relay 2TR, winding of relay ANR, front contact 30 of relay ANR, and contact 3| of button ANX closed in a normal and a depressed position, to The picking up of relay ANR causes the intermittent energization of the indicator lamp ANE (contained in the button ANX) by the energization of a circuit closed from including contact 32 of coder CD, wire 13, back contact 33 of relay AG, front contact 34 of relay ANR, and lamp ANE, to

The picking up of relay ANR also causes the picking up of relay CXK because of the energization of a circuit closed from (-l-) including front contact 35 of relay ANR. wire 80, back contact 36 of relay R, back bontact 31 of relay CNR, back contact 3B of relay CXR, and winding of relay CXK, to When relay CXK is picked up, the indicator lamp CXE is illuminated by the energization of an obvious circuit closed at front contact 39.

Relay DXK is also picked up responsive to the picking up of relay ANR by the energization of a circuit closed from (-5-) ,including front contact 35 of relay ANR, Wire 8B, back contact 43 of relay AN, back contact 4l of relay BN, back contact 42 of relay BY, back contact 43 of relay DNR, back contact 44 of relay DXR, and Winding of relay DXK, to When relay DXK is picked up, lamp DXE is illuminated by the energization of an obvious circuit closed at front contact 45.

When the operator depresses the button DNX for the exit end of the route he wishes to establish (from signal A to signal D), the relay DXR is picked up by the energization of a circuit closed from (-l-), including front contact 35 of relay ANR, wire 80, back contact 4D of relay AN, back contact 4l of relay BN, back contact 42 of relay BY, back contact 43 of relay DNR, Winding of relay DXR, front contact 46 of relay DXK, and contact 41 of button DNX closed in a depressed position, to Upon the picking up of relay DXR a stick circuit is closed at front contact 48 to shunt contacts 45 and 41 out of the circuit just described, thus maintaining relay DXR picked up after the button DNX is restored to its normal position.

When the final exit relay DXR is picked up,

the preliminary exit relay DXK is dropped away and signal A cleared for governing entrance to because of the opening of the circuit for that that route for an east bound train. relay at back Contact 44, and the dropping away When relay AG is picked up, the indicator of that relay causes the available exit point inlamp ANE becomes steadily energized by e, eirdioator lamp DXE to be extinguished beoause cuit closed from (-l-l, including front contact of the opening of the circuit for that indicator 33 ef relay AG,y from; Contact 34 ef relay ANR lamp at front contact 45. Suicient slow action and lamp ANE, te iS provided in the droppin,r aWay f relay DXK To consider as another example of how a t0 insure the ClQSng Of the Stick Circuit for relay rgute can be established through the track lay- DXR prior t0 the opening of the piek-11p Cir- 10 out, assume that the normal conditions of the Cuit fOr that relay at fIOilt COIltaCt 45 system exist as they have been described except Upon the picking up of relay DXR, the Switch the track switches TSA and TSB of the crosscontrol relay R is picked up by the energization over 'TS are in their reverse positions. Under 0f a CirCl-lit ClOSed from (-I- s including front C011- such conditions, assume that an operator desires tact 49 0f relay DXR, beek ContaCt 50 0f relay l5 to set up a route from signal B to signal D, and BY. upper winding of relay R, back Contact that he initiates the establishment of such route of relay AN, and baek Contact 52 of relay BN, by depressing the button BNX, thus causing the to energization of the relay BNR, by a circuit sim- ReSponSiVe t0 the DiCkiIlg up 0f relay R, reilar to the circuit which has heretofore been lay WZ (See Fig- 2) iS pioked l-lp With tS polar 20 described for the energization of relay ANR. in Contacts operated t0 a left hand position in aC- accordance with depression of button ANX.

cordance with the energization of a circuit closed Upon the pleking up 0f relay BNR the indicator from including front contact of relay lamp BNE Starts te flash te indicate that en- 2L, front contact 2l of relay 3L, front ContaCt trance designation has been effective for an en- 53 of relay R, and lOWer Winding 0f relay WZ, 25 trance point at signal B. The picking up of to (-l. The picking up of relay WZ, due to relay BNR causes the picking up of the relay such enereization. closes an obvious circuit ai BY by the energizaticn of a circuit closed from front contacts 54 and 55 to energize the switch (4.), including from; contact 10 0f relay BNR, machine SM With the proper polarity to Cause wire 82, back contact 'H of relay R, and winding its Operation to a IeVerSe position. of relay BY, to After relay BY is picked When the relay R iS peked 11p in the eStabup, relay DXK is picked up by the energization lishment of the route, the circuit for relay CXK of e eli-cuir, elesed from (-l )I including front (see Fig. 1B) is opened at back contact 36 be- Contact 1n ef relay BNR, (see Fig 1A), wire s2,

cause there is no longer an available route eX- back contact 'n of relay R, front contact 42 of tending from signal A to Signal C; and the droprelay BY, back contact 43 of relay DNR, back eine away of relay CXK causes the exit indicontact 44 of relay Dxa, and winding of relay cator lamp CXE to be extinguished because of DXK, te The picking up 0f relay DXK the opening of front Contact 39- causes the illumination of the lamp DXE in ac- Wherl the relay R iS picked up irl the estab' cordance with the energization of an obvious lishment of the route. the relay NCR (See Fig- 40 circuit closed at front contact 45, 2) is dropped aWay by the opening of back Upon observing the illuminated indicator lamp Contact 23, and the dropping away of that relay DXE, the operator knows that the route is availcloses a stick circuit for relay LS from inable extending from signal B, to Signal D, and he cluding front contact 20 of relay 2L, front condesignates the exit end ef that route by the de tact 2l 0f relay 3L back Contact 55 0f relay RCR 45 pression of button DNX. The depression of back Contact 5l of relay NCR, front Contact 53 button DNX causes the picking up of relay DXR 0f relay LS, and Winding 0f relay LS1 t0 (-lby the energization of a circuit closed from (-l-l,

After the operation of the track switches TSA including front Contact 'm of relay BNR, Wire 32, and TSB has been completed to a reverse locked back Contact 1| of relay R, front Contact q2 of position, the relay RC'R is picked up by the enso relay BY, back contact 43 of relay DNR, winding ergization of a circuit closed from includef relay DXR, front contact 46 of relay DXK, ing back Contact 5e of relay AN, back Contact and contact 41 of button DNX closed in a de- 50 0f relay BN winding of relay RCR, polar Conpressed position, to Upon the picking up of taet 24 of relay WP irl a left hand position and that relay a stick circuit is closed at front confront CoDtaCt 25 0f relay WP, t0 (-l The pick' 55 tact 48 to shunt contacts 46 and 4l out of the ciring up of relay RCR causes the dropping away cuit just described. The picking up of relay DXR of relay LS by opening the stick circuit for that also causes relay DXK to be dropped away berelay at back contact 56. cause of the opening of its circuit at back contact After the relay LS has been dropped away to 44, and the dropping away of relay DXK causes open the switch control circuit, the signal cone0 the indicator lamp DXE to be extinguished betrol relay AG (see Fig. 1A) is picked up by the Cause 0f opening front contact 45.

energization of a circuit closed from (-l-), in- Responsive lo the picking up 0f 'relai' DXR cluding front contact 6l of relay DXR (see Fig. relay BN 1S Picked up by the enerelzetlon 0f e 1B) from Contact 62 of relay 3TR front com circuit closed from including front contact t t I. 1 C back Contact sa of rela 65 49 of relay'DXR, front contact 5D of relay BY, DCCR slagk 'acRt 61g" of relay LS, Wire a', non?? upper winding of relay BN, and back contact 'l2 contact 66 of relay ZTR, back contact 6l of of relay R to It will be noted that the relay BN, rather than relay AKR front Contact 68 of r e135' ANR" and relay R, is picked up responsive to the energiza- Winding of relay AG' t0 (rl- .When lelay AG 70 tion of relay DXR because of the picked up posiiS picked up. the red lamp 111 Signal A 1S extln" tion of relay BY which is energized only when the glliSlled by the Opening 0f back Contact 59, and track switch TSB can be trailed in a normal pothe green lamp in that Signal iS illuminated by sition in an available route extending from an the closing of front contact 69. Thus, the route entrance point which has been designated.

from signal A to signal D is completely set up, Upon the picking up of relay BN, relay WZ (see Fig. 2) is picked up by the energization of a circuit closed from including front contact 2li of relay 2L, front contact 2| of relay 3L, iront contact 13 of relay BN, and upper winding of relay WZ, to When relay WZ is picked up due to such energization, the front contacts 54 and 55 close the control circuit for the switch machine SM to cause its operation to a normal position in accordance with the polarity by which relay WZ is energized. The relay RCR is dropped away upon the picking up of relay BN by the opening of its circuit at back contact 60, thus closing a stick circuit for relay LS which has been described for maintaining relay LS energized until the track switches TSA and TSB have been completely positioned. After the operation of the track switches has been completed to a normal position, the relay LS is dropped away to open the switch control circuit, and to close a circuit for the energization of the signal control relay BG, extending from (-1-) including front contact 6| of relay DXR (see Fig. 1B), front contact 62 of relay STR, back contact 53 of relay RCR, front contact 14 of relay NCR, back contact 15 of relay LS, wire B3, back contact 16 of relay Bm, front contact 11 of relay BNR, and winding of relay BG, to Upon the picking up of relay BG the red lamp in signal B is extinguished because of the opening of back contact 18, and the closing of front contact 13 causes the illumination of the green lamp in that signal.

Upon considering the circuit selections in the circuits which have heretofore been described for the energization of the relays Y, XK and XR, it will be obvious that the circuits are arranged in a network form which conforms in many respects to the track layout for which the system is provided. That is, the control circuit for relay DXR, when setting up a route from signal A to signal D extends from front contact 35 of relay ANR, over a branch of the initiating network corresponding to the crossover TS, including back contacts 40 and 4I of relays AN and BN, and such branch of the circuit is connected to the branch corresponding to the lower track in accordance with the selection on contact 42 of relay BY. When setting up a route from signal B to signal D, the relay DXR is energized through a branch of the circuit network which corresponds to the lower track, extending from front contact of relay BNR, through a selection on the relay BY which allows the tying in of the circuits for the two conflicting routes.

In order that the relays picked up only when DXR and DXK can be a route is available extending from that exit point to an entrance point which has been designated, selections on the relays AN, BN and R are provided in the initiating network in such a manner as to provide a check as to whether or not the track switches TSA and TSB are free to be operated to the required position for the route to be established. That is, if a route is established as has been described from signal B to signal D, the picked up position of relay BN opens the reverse branch of the initiating network at back contact 4I, because a route including those track switches in a reverse position is in conflict with the route already established; and similarly, the establishment of a route over the crossover TS causes the relay R to be picked up, and the picking up of that relay opens the normal branches of the initiating network to prevent the conditioning of a conflicting route by opening the initiating network at back contacts 36 and 1| corresponding to the upper and lower tracks, respectively. It is believed therefore apparent, because of the particular arrangement of the circuit selections in the initiating network, that a relay XK can be picked up only when there is no route established which conflicts with a route extending between that exit point and an entrance point which has been designated. Thus, if a route is set up from signal B to signal D, when an operator depresses the button ANX for designation of an entrance point for a route to be established, the relay CXK is picked up and the indicator lamp CXE is illuminated in accordance with the energization of circuits which have been described, but the indicator lamp DXE remains dark because the circuit for the energization of relay DXK is open at back contact 4I of relay BN. A similar condition exists when the route from signal B to signal D is occupied by a train and the entering signal B has been restored to stop as will be apparent hereinafter in the disclosure after considering the restoration of the system to normal.

Upon considering the accompanying drawings in view of the circ 'ts which have been described, it is believed to be obvious that a similar mode of operation is effective in the establishment oi routes for west-bound trailic, there being an initiating network for the control of the relays AY, AXK, AXR, BXK and BXR having circuit selections similar to the selections which have been described for the initiating network for eastbound trafilc, and arranged to conform to the track layout in the manner which has been described. The picking up of an exit relay XR when setting up a route for west-bound traflic causes the selective energization of the switch control relay AN, BN and R in a manner similar to that which has been described, such ener-gization being effective for the lower windings of those relays.

The same circuit network is used for the energization of the signal control relays G for westbound traffic as is used for east-bound traic in a manner which is believed to be obvious. inasmuch as the space on the control panel is limited, it is desirable to limit the contact requirements on the route end buttons NX, and thus it is provided in accordance with the present invention. that a contact closed only in the depressed position serves for the energization of an entrance relay for one direction of traffic and for the energization of an exit relay XR for the opposite direction of traiiic at the same route end. That is, the closing of contact 29 of button ANX, see Fig. 1A) causes the energization of relay ANR when an entrance point is designated for signal A, and that contact also serves to cause the picking up of relay AXR when that signal location is an exit point in the route being established. To consider how such contact causes the energization for relay AXR in setting up a route for a west-bound train, assume that the normal conditions of the system exist as they have been described, and assume that an operator designates an entrance point at signal D and thus causes the picking up of relay DNR (see Fig. 1B).

Upon the picking up of relay DNR, relay AXK is picked up by the energization of a circuit closed from (+L including contact 84 of relay DNRk back contact 85 of relay BN, back contact 85 of relay AN, wire IUI, back contact 31 oi relay AY, back contact 88 of relay ANR, back contact 8l! of relay AXR and winding of relay AXK, to The picking up 0f relay AXK causes illumination of the exit indicator lamp AXE upon cios.

ing an obvious circuit at front contact 99. Upon observing the illuminated indicator lamp AXE, the operator is informed that a route is available from signal D to signal A, and upon the depression of button ANX for designation of the exit point at signal A, the relay AXR. is picked up by the energization of a circuit closed from (-i-), including front contact 84 bf relay DNR (see Fig. 1B), back contact 85 of relay BN, back contact 86 of relay AN, wire IUI, back contact 81 of relay AY, back contact 88 of relay ANR, winding of relay AXR, front contact 23 of relay AXK and contact 29 of button ANX closed in a depressed position, to The picking up of relay AXR Closes a. stick circuit for that relay at front contact 9i to shunt contacts 28 and 29 out of the circuit just described.

The establishment of a route from signal D to signal A in accordance with the picked-up position of the relays DNR and AXR is accomplished in a manner similar to the general mode of operation of the system as heretofore described.

Restoration-The restoration to normal of the route establishing means can be initiated in two different ways, one of which is accomplished automatically upon the passage of a train past an entering signal to a route, and the other is effected in accordance with the manual designation by an operator of such restoration by the pulling out of the route end button NX for the entrance end of that route.

To consider first the restoration to normal in accordance with the manual designation of such restoration by an operator, assume that a route has been set up as heretofore described from signal A to signal D, and that signal A is clear. The pulling out of the button ANX by the opera-- tor causes the entrance relay ANR to be dropped away because of the opening of the stick circuit for that relay at normally closed contact 3l (see Fig. 1A). Upon the dropping away of relay ANR, the signal A is restored to danger in accordance with the dropping away of the signal control relay AG which has its circuit opened at front contact 68 of relay ANR. The restoration to stop of signal A causes the picking up of the route locking relays IZES and 3ES (see Fig. 2) and the picking up of those relays causes the picking up of the lock relays 2L and SL by the energization of obvious circuits described in detail in my above-mentioned prior application, Ser. No. 275,923, filed May 26, 1939.

The dropping away of relay ANR (see Fig. lA) also causes the dropping away of the exit relay DXR by opening the stick circuit for that relay at front contact 35, and the dropping away of relay DXR causes the dropping away of relay R. by opening the circuit for that relay at front contact 49 (see Fig. 1B). Upon the dropping away of relay R, relay WZ is dropped away (see Fig. 2) because of the opening of front contact 53, and the dropping away of that relay causes the picking up of relay LS by closing back contact 22, thus completing the restoration to normal of the relays associated with the establishment of a route from signal A to signal D.

To consider the restoration to normal in accordance with the passage of a train past the entering signal to a route, assume a route to have been set up from signal A to signal D, and assume an east-bound train to pass signal A and cause the dropping away of the track relay ZTR. The dropping away of the track relay ETR causes the droppingr away of relay ANR by opening the stick circuit for that relay at front contact 26, and the dropping away of relay ANR initiates the restoration to normal of the relays in a manner similai to that which has been described, except that the relay R is maintained energized while the train is in the route by stick circuits energized dependent upon the deenergization of the lock relays 2L and 3L (see Fig. 2) which are, of course, deenergized as long as the route locking is effective to cause respectively relays ZES and 3ES to be deenergized. The route locking relays are deenergized for all track sections included in a route established in advance of a train in accordance with the usual practice of route locking.

The relay R is maintained energized under such conditions by a circuit closed from (-1-), including back contact 92 of relay 2L, front contact 93 of relay R, back contact 94 of relay AN, center winding of relay R and back contact 95 of relay BN, to After the train leaves track section 2T, the relay R is still maintained energized by the energization of a circuit closed from (-f-) including back contact 96 of relay 3L, front contact 91 of relay R, back contact S4 of relay AN, center winding of relay R, and back contact 95 of relay BN, to

After the train has left the route, both of the stick circuits for relay R which have been described are deenergized by the picking up of the relays 2L and 3L to open the stick circuits at back contacts 92 and 96 respectively, and the dropping away of those relays causes the restoration to normal of the relays WZ and LS in a manner which has been described.

If in practice, it is required that indications be displayed on the track diagram by lines of light corresponding to the routes established, it may be desirable to modify the control of the exit indicator lamps from the form shown in Fig. 1A to the form shown in Fig. 3. In such modification, the light section adjacent each exit point becomes an exit indicator, such section being illuminated upon designation of an entrance point for an available route extending to that exit point. When the route is established, however, the same light section provides a route indication. The indications provided in accordance with Fig. 3, therefore, differ from the exit indications shown in Fig. 1 in that each exit indicator lamp remains illuminated to provide a route indication when a route is established including that exit point.

With reference to Figs. 3A and 3B, each of the relays NR for the entrance end of each route is governed in a manner similar to that shown in Fig. 1A, and each of the relays XK1 (see Fig. 3B) is governed by a circuit similar to the circuit for each of the relays XK as shown in Fig. 1A, except for the omitting in that circuit of a back contact of the exit relay XR for that exit point. That is, for example, the relay AXK1 (see Fig. 3B) has the same control circuit as the relay AXK (see Fig. 1A) except that back contact 89 of relay AXR is omitted from that circuit. Thus, for example, in setting up a route from signal D to signal A, the picking up of relay DNR causes the energization (according to Fig. 3B) of relay AXK1 by a circuit closed from (-1-), including front contact B4 of relay DNR (see Fig. 1B), back contact of relay BN, back contact 86 oi relay AN, wire IBI, back contact 81 of relay AY, wire 98, (see Fig. 3B) back contact 88 of relay ANR, and winding of relay AXKI, to Such circuit causes the relay AXK1 to remain energize-d, dependent for deenergization upon the dropping away of the entrance relay DNR.

After the picking up of relay AXK1 (see Fig. 3B) the depression of the button ANX for designation of the exit point for the route from signal D to signal A causes the picking up of the exit relay AXR1 by the energization of a circuit closed from (-l) including winding of relay AXRJ, iront contact 20 of relay AXK, and contact 29 of button ANX closed in a depressed position, to The picking up of that relay causes a stick circuit to be closed at front contact 99 to shunt contact 29 out of the circuit just described, thus making the restoration of relay AXR1 dependent upon the dropping away of relay AXK.

It is to be understood that, where the indications are displayed by lines of light in accordance with the circuits shown in Fig. 3A, the relays for each of the route ends have their control circuits provided in a manner corresponding with the circuits shown and described associated with the route end at signal A.

As a means for displaying indications by lines of light, light sections 2, 3, 4, 5, 6, 1 and 3 are provided along the track diagram, each section being uniformly illuminated by either a white or a red lamp mounted back of a translucent strip that extends throughout the length of the light section. The light sections 2, 3, 4 and 5 are provided for indicating exit points aavilable for their respective route ends A, C, B and D, and also for the purpose of indicating routes established and track occupancy. The light sections 6, 1 and B are provided for indicating the locked and outof -correspondence positions of the track switches TSA and TSB of the crossover TS, and they also provide an indication as to track occupancy. The light sections 5 and 8, when steadily illuminated by a white lamp indicate the establishment of a route through that respective track portion with the track switches TSA and TSB locked in a normal position, and the light section 1, when steadily illuminated with a White lamp, indicates the establishment of a route over the crossover with the track switches locked in their respective reverse positions. The iiashing of the white indicator lamp for either of the light sections 6, 1 or 3 indicates that such position of the track switch has been called for, but the operation of the track switch to that position has not been completed. The passage of a train through each of the routes causes a track occupancy indication to be displayed for the section of such route included in the track section which is occupied by that train, such indication being provided by l the illumination of a red lamp for each of the light sections involved.

To consider more speciilcally how the circuits provide the indications which have been described in a general manner, assume that, when normal conditions exist as they have been described, an operator designates an entrance point at signal A for the establishment of a route. The picking up of relay ANR in accordance with such designation causes the picking up oi a relay XK1 for each yof the exit points C and D by the energization of circuits provided in accordance with the circuit selections described as typical for the energization of relay AXK.

The picking up of relay CXK1 causes the i1- lumination of the light section 3 because of the energization of the white lamp 3WE by a circuit closed from (-I-), including front contact |02 oi relay CXK, front contact |03 of relay 2L, front contact |04 of relay 2TR, and white lamp 3WE, to

The light section 5 is illuminated because of the energization of the white lamp EWE by a circuit closed upon the picking up of relay DXK1, from (-5-), including front contact |05 of relay DXKI, front contact |06 of relay 3L, front contact |01 of relay 3TR, and lamp 5WE, to

Upon the designation of an exit point at signal D, subsequent to the designation of an entrance point at signal A, by the depression of the button DNX, the route extending from signal A to signal D is established and the entering signal A cleared in accordance with a mode of operation which has been heretofore described. The picking up of relay R (see Fig. 1B) in the establishment of that route causes the dropping away of relay CXK1 because -of the opening of the circuit for that relay at back contact 36, the control circuit for relay CXK1 corresponding with the control circuit for relay CXK except that back contact 30 of relay CXR is eliminated. The dropping away of relay CXK1 causes the white lamp 3WE in light section 3 to be extinguished because of the opening of the circuit for that lamp at front contact |02. The light section 5 remains illuminated, however, because, in accordance with the modification shown in Fig. 3B, the exit relay DXK1 is not deenergized upon the picking up of the exit relay DXR for that exit point.

The light section 2 becomes illuminated when relay R is picked up upon the energization of a circuit for lamp 2WE, closed from including front contact |22 of relay R, front contact |24 of relay ANR, back contact |25 of relay AIQl, front contact II3 of relay 2L, front contact II4 of relay 2TR, and lamp 2WE, to

In the establishment of a route from signal A to signal D, under the conditions assumed, the picking up of relay R causes the light section 1 to be illuminated because of the intermittent energization of the white lamp 'IWE by a circuit closed from (-I-), including back contact |08 of coder CD, back contact |09 of correspondence relay RCR, front contact |I0 of relay R, lamp 1WE, front contact III of relay 3TR, and front contact. II2 of relay 2TR, to As soon as the track switches TSA and TSB of the crossover TS are operated to their reverse locked positions (in accordance with the reverse control called for by the picking up of the relay R) the relay RCR is picked up, and the light section 1 becomes steadily illuminated in accordance with the energization of lamp 1WE by a circuit closed from including front contact |09 of relay RCR, front contact ||0 of relay R, lamp 1WE, front contact I I I of relay 3TH., and front contact II2 of relay 2TR, to A line of white light is thus completely established corresponding to the route set up from signal A to signal D.

Upon the clearing of signal A, the route locking becomes effectivefor the route established from signal A to signal D, thus causing the relays 2L and 3L to be dropped away. Upon the dropping away of relay 2L, a circuit is closed for the energization of the lamp 2WE of light section 2, from including back contact I I3 of relay 2L, front contact II4 of relay 2TR and lamp 2WE, to The dropping away of relay 3L closes a circuit for the energization of lamp SWE in light section 5, from including back contact |05 of relay 3L, back contact |01 of relay 3TH, and lamp EWE, to The energization of such circuits for the lamps WE of light sections 2 and 5 respecpreaching train.

When the train tact locking for that 2L is picked up. thus providing that the circuits for both of the lamps in light section 2 back contact ||3 of relay 2L.

closes a circuit for lamp '|RE, from including back contact ||5 of relay NCR, "IRE, back contact 3TR, and contact ||2 of relay ZTR, to

lamp front circuit for the White lamp TWE of that light secthe dropping away of relay R at with circuits heretofore described for relays AXR1 and AXK1 as shown in Fig. 3.

The picking up of relay DXKI,

The circults which have been lamp EWE in accordance with the energization of a circuit which has been described.

The ligh section 4 becomes illuminated when of relay BN, front contact |21 |28 of relay B-XKI, contact |30 reverse) by back contact of relay BN, lamp contact |2| of relay BTR, to

cluding back contact tact |29 of relay 3L, front contact |30 of relay STR, and lamp 4WE, to Back contact |22 of relay R in that circuit provides that light sections 3 and 4 remain dark when a route is tion 0i a circuit closed from including back contact |22 of relay R, back contact |29 of relay 3L, back contact |30 of relay STR, and lamp 4RE, to The lamp SWE is illuminated by the of a circuit closed from (+L includingr back contact |23 of relay RCR, red lamp BRE, contact |2| of relay cuit which has been described.

When the train leaves the route established,

' is effective Summary From the foregoing description it will be obvious that, in the novel features provided by the present invention, the exit relays XK, controlled by initiating networks of the character described, play an important part. That is, for example, the energization of an entrance relay NR or an exit relay XR in accordance with the depression of the control button NX for that route end is selected in accordance with the respective dropped away or picked up position of the relay XK for that route end.

Inasmuch as an exit indicator lamp is illuminated for each route end in accordance with the picking up of each of the relays XK, an operator is definitely informed, upon considering such indicator lamp for each route end, whether the depression of the button NX for that route end will denne an entrance or an exit point,

lt is further provided by the control of each of the exit indicator lamps that such lamp is illuminated only if there is a route available for use extending from that exit point to an entrance point which has been designated. Such control of each of the lamps is provided in accordance with the circuit organization of the initiating networks, which provides that energy feeds through each branch of a circuit network, only so far as such branch deiines by circuit selections that that branch corresponds with an available route extending from an entrance point which has been designated.

It is therefore believed that it will be readily understood, in view of the universal application of the route establishing means as described more in detail in my prior application Ser. No. 275,923, filed May 26, 1939, and in the patent to A. Langdon, Patent No. 2,148,865, dated February 28, 1939, that the present invention is applicable to practically any complex track layout encountered in practice. It is also to be understood that the novel features relative to the exit indications can also be applied to entrance-exit systems in which separate entrance and exit buttons are provided for each route end; and that the relays XK can be used in entrance-exit systems in which only one button is provided for each route end for selecting the control of the entrance and exit relays, irrespective of the indications provided.

Having described the present invention as applied to an entrance-exit system for governing a simple track layout, as one specific embodiment of the present invention, it is desired to be understood that this form is selected to facilitate in the disclosure of the invention rather than to limit the number of forms which the invention may assume; and it is to be further understood that various adaptations, alterations, and modifications may be applied to the specific form shown to meet the requirements of practice, without in any manner departing from the spirit or scope of the invention, except as limited by the appending claims.

What I claim is:

1. In a switch and signal control system of the entrance-exit type for governing from a control ofiice the establishment of each route extending through a track layout between entrance and exit points; manually operable contact means for each of the entrance and exit points; a preliminary exit relay for each of said exit points; circuit means responsive to the actuation of said contact means for any given entrance point for energizing said preliminary exit relay for the exit point of each route available for use extending from the designated entrance point, such circuit means being effective to deenergize that preliminary exit relay Whenever said contact means for a particular one of said available exit points is actuated; an indicator lamp for each of the exit points; and circuit means for energizing each of said indicator lamps in accordance with the energized condition of said preliminary exit relay for the corresponding exit point.

2. In a switch and signal control system o the character described for the establishment of each desired route extendmg through a track layout between entrance by the power operation of track sw1tches and/or crossovers; a single manually operable contacter for each of the route ends; an entrance relay for each of the entrance points; a rst and a second exit relay for each of the exit points; circuit means responsive to the actuation of said contactor for energizing said entrance relay for that route end, only if said first exit relay for that route end is deehergized; stick circuit means for maintaining said entrance relay for each entrance point energized dependent upon the manually operable contact means for that entrance point; circuit means responsive to the energization of said entrance relay for each entrance point for energizing said rst exit relay for each of the exit points that can be included in an available route emanating from such entrance point, such circuit means being effective to deenergize that first exit relay when said second exit relay for that exit point is energized; circuit means responsive to the actuation of said contactor for each of the route ends for energizing said second exit relay for that route end, only if said first exit relay for that route end is energized; stick circuit means for maintaining said second exit relay for any exit point energized dependent upon the energized entrance relay for the route terminating at that exit point; and route establishing means including separate normal and reverse switch control relays for each of the track switches and/or crossovers responsive to the joint energization of said entrance and said exit relays for the respective entrance and exit ends of each route for causing the power operation of the track switches to establish such route, said route establishing means providing interlocking between conflicting routes by contacts of said normal and reverse relays so as to allow only one of several conflicting routes to be established at a time.

3. In a switch and signal control system of the character described for the establishment of any desired route extending through a track layout providing by power switches a plurality of conflicting routes extending between entrance and exit points at route ends', a signal for governing entrance to each of the routes; a single manually operable contactor for each of the route ends; an entrance relay for each of the entrance points; a preliminary and a final exit relay for each oi the exit points; circuit means responsive to the actuation of said contactor for designation of an entrance point for energizing said entrance relay for that point only if said final exit relay for that route end is deenergized; stickcircuit means for maintaining each of said entrance relays tive entrance and exit ends of each of the routes energized dependent upon tlie manually operable for causing the power operation of the track contactor for that entrance point; circuit means switches to establish such route.

responsive to the energization of each of said en- 5. In a switch and signal control system of trance relays for energizing said preliminary exit 5 the entrance-exit type for governing the power relay for the exit end of each available route operation of track switches from a control oce originating at the corresponding entrance point, to establish different routes through a track laysuch circuit means being eiective to deenergize out between entrance and exit points, manually any given preliminary exit relay when its assooperable contact means for each of the entrance ciated inal exit relay for that exit point is enerl0 and exit points, a relay for each of the exit points, gized, circuit means responsive to the actuation conditioning circuit means responsive to the of said contactor for the exit end of an available actuation of said contact means to designate any route for energizing said nal exit relay for given entrance point for energizing said relay that route, only if said preliminary exit relay for for the exit end of each available route originatthat route end is energized, stick circuit means ing at that entrance point, an indicator lamp foi' tor maintaining said nal exit relay for any exit each of said exit points. circuit means controlled point energized dependent upon the energized by each relay when energized for energizing its entrance relay for the route terminating at that respective lrldlCaOI lamp and Circlllt means reexit point, an entrance and an eXit indicator lamp sponsive to the actuation of the contact means for each of the route ends; circuit means responfor any exit point at the end of an available for each entrance point for intermittently enercausing the operation of the track switches to gizing said entrance indicator lamp for that establish that route, said circuit means also actroute end, circuit means responsive to the enering on said conditioning circuit means to deenerof any given route for causing the power operaation of the track switches in a track layout to and clear the signal governing entrance thereto constituting entrance and exit points, a single and circuit means responsive to the clearing of push button manually operable to either of two each of the signals for causing said entrance mdierent actuated positions for each of said sigdicator lamp for that entrance point to become nal locations, an entrance relay for each of the steadily energized. signal locations constituting an entrance point,

4. In a switch and signal control system of a rst and a second exit relay for each of the sigthe entrance-exit type for the setting up of any nal locations constituting an exit point, circuit which provides by power switches a plurality of push button to designate its signal location as operable contactor for each of the route ends an that route end is deenergized, stick circuit means entrance relay for each of the entrance points, for maintaining said entrance relay energized dea rst and a second exit relay for each of the pendent upon its push button unless such push exit points circuit means responsive to the acbutton is operated to its opposite actuated posituation of said contactor for designation of an tion, conditioning circuit means responsive to the entrance point foi energizing said entrance reenergization of the entrance relay for any given lay for that point only if said second exit relay entrance point for energizing said rst exit relay for that route end is deenergized; stick circuit for the exit end of each available route originatmeans for maintaining each of said entrance reing at that entrance point, circuit means responlays energized dependent upon the manually sive to the actuation of the push button for the operable contactor for that entrance point, cirsignal location at the exit end of any one of said cuit means responsive to the energization of each available routes having its first exit relay enerof said entrance relays for energizing each of gized for causing the energization of the second said irst exit relays, only if there is an available exit relay for that route end and thereby deenerroute extending between the entrance point degize its associated first exit relay, stick circuit signated and that exit point, such circuit means means responsive to the picking up of said second that first exit relay when said second exit relay 6o dependent upon the continued energization of of the exit points; circuit means dependent upon picked up condition of the entrance relay at the the energization of said first exit relay for each entrance end of that route. of the exit points for energizing said exit indi- 7. In a switch and signal control system of the cater lamp for that exit point and route estabentrance-exit type for governing the power operand exit signal locations, a miniature track diagram of said track layout, a single manually operable push button located on said track diagram at each point corresponding to a signal location, miniature movable switch points on said track diagram at points corresponding to the actual track switches, an entrance relay for each of the signal locations, a preliminary exit relay and a final exit relay for each of the signal locations, circuit means responsive to the actuation of any given push button to designate its signal location as an entrance point for energizing the corresponding entrance stick relay, stick circuit means for maintaining said entrance relay energized dependent upon a different actuation of the same push button, initiating circuit means responsive to the energization of an entrance relay for energizing the preliminary exit relay for the exit end of each available route originating at the corresponding signal location, an indicator lamp located on said track diagram adjacent each of said manually operable push buttons and energized when the corresponding preliminary exit relay is energized,

circuit means responsive to the actuation of a push button for the exit end of any available route for causing the energization of the nal exit relay for that route end for opening a contact to cause the deenergization of the associated preliminary exit relay, stick circuit means responsive to the picking up of said nal exit relay for rendering such relay dependent upon the continued energization of said initiating circuit means, and route establishing means responsive to the picked-up condition of said final exit relay for any given route for causing the proper positioning of said miniature movable switch points on said track diagram for the switches in that route and also causing the power operation o the actual track switches of the track layout to establish that route and clear the signal at the entrance thereto, said circuit means also acting on said initiating circuit means to deenergize all of the remaining preliminary exit relays which were energized in response to the picking up of the entrance relay for the entrance end of the designated route.

SEDGWICK N. WIGHT. 

